springboot实现上传文件与下载文件

一、 上传文件

1. 概述

springboot实现文件的上传，主要分为2种方式：1、通过数据库存取文件的url实现存取与读取2、通过数据库存取文件进行操作，下面我将主要讲述方式1

2. 代码实现

yml配置文件

file:
  # 本地windows
  #location: E:/idea-download/
  #linux服务器
  location: /usr/local/apps/pmxt-download/
  path: /download/**
#  domainname: http://43.142.87.68:9001
  domainname: http://localhost:9001

location为服务器实际存储地址，path为通过URL地址的访问路径，两者是对应的

配置文件

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;


@Configuration
public class FileDownloadConfig implements WebMvcConfigurer {
    @Value("${file.location}")
    String filelocation;
    @Value("${file.path}")
    String filepath;

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        //匹配到resourceHandler,将URL映射至location,也就是本地文件夹
        registry.addResourceHandler(filepath).addResourceLocations("file:///" + filelocation);//这里最后一个/不能不写
    }

}

上述的配置文件也可以通过yml实现，如下图（web上级为spring）：

这里主要是将服务器实际地址与URL对应

Controller

import com.example.pmxt.common.ReturnResult;
import com.example.pmxt.domain.Auctioneer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;

@RestController
@RequestMapping("/auctioneers")
@Validated
public class AuctioneerController {

//获取yml里配置好的变量
    @Value("${file.location}")
    String filelocation;
    @Value("${file.path}")
    String filepath;
    @Value("${file.domainname}")
    String domainname;
    private final AuctioneerService auctioneerService;

    @Autowired
    public AuctioneerController(AuctioneerService auctioneerService) {
        this.auctioneerService = auctioneerService;
    }

    @GetMapping()
    public ReturnResult getauctioneerall(){
        return ReturnResult.buildSuccessResult(auctioneerService.list());
    }

    @GetMapping("/{pmsbh}")
    public ReturnResult getbypmsbh(@PathVariable @Validated String pmsbh){
        Map<String,Object> map = new HashMap<>();
        map.put("pmsbh",pmsbh);
        return ReturnResult.buildSuccessResult(auctioneerService.listByMap(map));
    }

    @PostMapping()
    public ReturnResult addauctioneer(@RequestBody @Validated Auctioneer auctioneer){
        try {
            // 获取文件名
            String FileName = auctioneer.getPmszsz().substring(auctioneer.getPmszsz().lastIndexOf("/"));
            // 复制文件
            Files.copy(Paths.get(filelocation + "/auctioneer/temp/" + FileName), Paths.get(filelocation + "/auctioneer/" + FileName));
            // 删除临时文件
            Files.delete(Paths.get(filelocation + "/auctioneer/temp/" + FileName));
            // 保存新的url
            auctioneer.setPmszsz(auctioneer.getPmszsz().replace("/temp",""));
            // 存入数据库
            if(auctioneerService.save(auctioneer)){
                return ReturnResult.buildSuccessResult(1);
            }
            else{
                return ReturnResult.buildSuccessResult(0);
            }
        }
        catch (IOException e){
            return ReturnResult.buildFailureResult("logo/officialSeal 文件url不正确");
        }
    }

    @DeleteMapping("/{id}")
    public ReturnResult deletebyid(@PathVariable @Validated Integer id){
        return ReturnResult.buildSuccessResult(auctioneerService.removeById(id));
    }

    @PutMapping()
    public ReturnResult updateauctioneer(@RequestBody @Validated Auctioneer auctioneer){
        return ReturnResult.buildSuccessResult(auctioneerService.updateById(auctioneer));
    }

    @PostMapping("/addpmszhz")
    public ReturnResult addCarousel(MultipartFile file) {
        if (file == null || file.isEmpty()) {
            return ReturnResult.buildFailureResult("请传入文件");
        } else {
            try {
                // 保存图片
                // 服务器文件名
                String serverFilename = UUID.randomUUID().toString().substring(0, 8)
                        + file.getOriginalFilename().substring(file.getOriginalFilename().lastIndexOf("."));
                // 创建目录、存储图片地址目录
                String path = filelocation + "/auctioneer/temp/";
                // 存储图片的url
                Files.createDirectories(Paths.get(path));
                // 保存
                file.transferTo(Path.of(path, serverFilename));
//这里是将URL返回给了前端，实际上也可以传到数据库，不过那样就其他的值也要一起传进来
                return ReturnResult.buildSuccessResult(domainname + "/download/auctioneer/temp/" + serverFilename);

            } catch (Exception e) {
                e.printStackTrace();
                return ReturnResult.buildFailureResult(e.toString());
            }
        }
    }
}

二、下载文件

概述

一般来讲对于文件的下载只要给前端文件地址就好了，但是在修改jeecgboot框架时，发现文件只有PDF与图片格式能够打开并下载，而word与excel格式则无法打开下载，后来仔细查了一下，因为浏览器自带PDF与图片浏览插件，所以能够查看下载，而word与excel则只能下载，但是总是报401，token失效，后来仔细查了一下是因为前端把jeecgboot文件下载地址改了，由于没有在特定的地址下，所以受到了拦截器，而且token失效，但是当时以防万一自己也是写了个下载接口

导入依赖

    // https://mvnrepository.com/artifact/commons-io/commons-io
    implementation 'commons-io:commons-io:2.11.0'

写定下载静态方法

public static void downloadByCommonIO(String url, String saveDir, String fileName) {
        try {
            FileUtils.copyURLToFile(new URL(url), new File(saveDir, fileName));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

Controller接口

@PostMapping("/download")
    public ReturnResult downloadFile(){
        downloadByCommonIO("http://101.42.99.134:8888/jeecg-boot/sys/common/static/temp/46f630ac.xlsx","E:/桌面/新建文件夹","test.xlsx");
        return ReturnResult.buildSuccessResult(true);
    }

参考文档：https://blog.csdn.net/m0_46360888/article/details/128022927